H1N1 Gets Another New Name; well, sort of: Triple-Reassortant Swine Flu

Here is something I am sure the pork-producers are not going to like to hear. From my reading of this pro-med update that I received today, it sounds as if they have traced the orgins of H1N1 to, (of all things) swine! Of course, they are quick to say that at this point, its only "hypothesized," but here have a look at the evidence for yourself (below) I would say that it is more than circumstantial and enough to make a believer out of me. Pigs mutated that germ and are spreading it to humans, and then humans are spreading it to other humans, and maybe even to birds and who knows what other animals can catch it?
Be sure and read all the way down where it says;

Pigs have been hypothesized to act as a mixing
vessel for the reassortment of avian, swine, and
human influenza viruses and might play an
important role in the emergence of novel
influenza viruses capable of causing a human
pandemic.I

So, ah, does this mean we have to change the name back to swine flu again, only this time call it Rriple-Reaaaortant" Swine Flu?

NFLUENZA A (H1N1) - WORLDWIDE (19)
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In this update:
[1] Triple-reassortant swine flu (ex NEJM)
[2] Emergence of novel strain (ex NEJM)

******
[1] Triple-reassortant swine flu
Date: Thu 7 May 2009
Source: The New England Journal of Medicine [edited]



Triple-Reassortant Swine Influenza A (H1) in
Humans in the United States, 2005­2009
-----------------------------------------------------------------------------------
Introduction
------------
Pigs have been hypothesized to act as a mixing
vessel for the reassortment of avian, swine, and
human influenza viruses and might play an
important role in the emergence of novel
influenza viruses capable of causing a human
pandemic. Recent reports of widespread
transmission of swine-origin influenza A (H1N1)
viruses in humans in Mexico, the United States,
and elsewhere highlight this ever-present threat
to global public health. Between the 1930s and
the 1990s, the most commonly circulating swine
influenza virus among pigs -- classic swine
influenza A (H1N1) -- underwent little change.
However, by the late 1990s, multiple strains and
subtypes (H1N1, H3N2, and H1N2) of
triple-reassortant swine influenza A (H1) viruses
-- whose genomes included combinations of avian,
human, and swine influenza virus gene segments --
had emerged and became predominant among North American pig herds.

Influenza virus infection was identified as a
cause of febrile respiratory illness in pigs as
early as 1931, 3 years before influenza viruses
were identified as a cause of illness in people.
Classic swine influenza viruses are enzootic
among pigs in North America. Cases and clusters
of human infections with swine influenza viruses
have been reported sporadically in the United
States since the 1970s. Worldwide, more than 50
cases of swine influenza virus infection in
humans, most due to classic swine influenza
virus, have been documented in the past 35 years,
and serologic studies suggest that people with
occupational swine exposure are at highest risk for infection.

Before the current epidemic of swine-origin
influenza A (H1N1) viruses, illness from classic
swine influenza viruses, including 7 deaths, had
been reported in both previously healthy persons
and those with preexisting medical conditions
(including pregnancy). Signs and symptoms of
infection with classic swine influenza virus in
humans are often indistinguishable from those of
infection with human influenza viruses. Until
April 2009, only limited, nonsustained
human-to-human transmission of swine influenza virus had been reported.

Outside the United States, there have been 2
published case reports of human infection with
triple-reassortant swine influenza A (H1) viruses
(both subtype H3N2). Before 2005, the Centers for
Disease Control and Prevention (CDC) had been
receiving approximately one or 2 case reports of
human infection with classic swine influenza
viruses per year. The CDC identified the 1st
human infection with triple-reassortant swine
influenza A (H1) viruses in the United States in
December 2005. In June 2007, human infection with
a novel influenza A virus (including influenza
viruses of animal origin) was classified as a
nationally notifiable infectious disease in the
United States. From December 2005 through
February 2009, the CDC received 11 notifications
of human infection with triple-reassortant swine
influenza A(H1) viruses, 8 of which occurred
after June 2007. In this article, we characterize
the epidemiologic and clinical features of the
1st 11 cases in humans reported in the United
States between December 2005 and February 2009.
An additional human case of infection with
triple-reassortant swine influenza A (H1) viruses
was detected in South Dakota in January 2009 but
is not described here, because serologic studies
for the patient and the patient's contacts are
pending finalization of the serologic assay for
infection with triple-reassortant swine influenza A (H1) viruses.

Abstract
--------
Background: Triple-reassortant swine influenza A
(H1) viruses -- containing genes from avian,
human, and swine influenza viruses -- emerged and
became enzootic among pig herds in North America during the late 1990s.

Methods: We report the clinical features of the
1st 11 sporadiccases of infection of humans with
triple-reassortant swine influenza A (H1)
viruses, occurring from December 2005 through
February 2009, until just before the current
epidemic of swine-origin influenza A (H1N1) among
humans. These data were obtained from routine
national influenza surveillance reports and from
joint case investigations by public and animal health agencies.

Results: The median age of the 11 patients was 10
years (range, 16 months to 48 years), and 4 had
underlying health conditions. 9 of the patients
had had exposure to pigs, 5 through direct
contact and 4 through visits to a location where
pigs were present but without contact. In another
patient, human-to-human transmission was
suspected. The range of the incubation period,
from the last known exposure to the onset of
symptoms, was 3 to 9 days. Among the 10 patients
with known clinical symptoms, symptoms included
fever (in 90 percent), cough (in 100 percent),
headache (in 60 percent), and diarrhea (in 30
percent). Complete blood counts were available
for 4 patients, revealing leukopenia in 2,
lymphopenia in one, and thrombocytopenia in
another. 4 patients were hospitalized, 2 of whom
underwent invasive mechanical ventilation. 4
patients received oseltamivir, and all 11 recovered from their illness.

Conclusions: From December 2005 until just
before the current human epidemic of swine-origin
influenza viruses, there was sporadic infection
with triple-reassortant swine influenza A (H1)
viruses in persons with exposure to pigs in the
United States. Although all the patients
recovered, severe illness of the lower
respiratory tract and unusual influenza signs
such as diarrhea were observed in some patients,
including those who had been previously healthy.

[Byline: Vivek Shinde, M.D., M.P.H., Carolyn B.
Bridges, M.D., Timothy M. Uyeki, M.D., M.P.H,
M.P.P., Bo Shu, B.S., Amanda Balish, B.S., Xiyan
Xu, M.D., Stephen Lindstrom, Ph.D., Larisa V.
Gubareva, M.D., Ph.D., Varough Deyde, Ph.D.,
Rebecca J. Garten, Ph.D., Meghan Harris, M.P.H.,
Susan Gerber, M.D., Susan Vagoski, D.V.M.,
Forrest Smith, M.D., Neal Pascoe, R.N., Karen
Martin, M.P.H., Deborah Dufficy, D.V.M., M.P.H.,
Kathy Ritger, M.D., M.P.H., Craig Conover, M.D.,
Patricia Quinlisk, M.D., M.P.H., Alexander
Klimov, Ph.D., Joseph S. Bresee, M.D., and Lyn Finelli, Dr.P.H.]

--
Communicated by:
ProMED-mail


******
[2] Emergence of novel strain
Date: Thu 7 May 2009
Source: The New England Journal of Medicine [edited]



Emergence of a Novel Swine-Origin Influenza A (H1N1) Virus in Humans
--------------------------------------------------------------------
Introduction
------------
Triple-reassortant swine influenza viruses, which
contain genes from human, swine, and avian
influenza A viruses, have been identified in
swine in the United States since 1998, and 12
cases of human infection with such viruses were
identified in the United States from 2005 through
2009. On 15 Apr 2009 and 17 Apr 2009, the Centers
for Disease Control and Prevention(CDC)
identified 2 cases of human infection with a
swine-origin influenza A (H1N1) virus (S-OIV)
characterized by a unique combination of gene
segments that had not been identified among human
or swine influenza A viruses. As of 5 May 2009,
cases of human infection with the same novel
virus have also been identified in Mexico,
Canada, and elsewhere. We report the 1st 643
confirmed cases of human infection with this virus in the United States.

Abstract
--------
Background: Triple-reassortant swine influenza
viruses, which contain genes from human, swine,
and avian influenza A viruses, have been
identified in swine in the United States since
1998, and 12 cases of human infection with such
viruses were identified in the United States from
2005 through 2009. On 15 Apr 2009 and 17 Apr
2009, the Centers for Disease Control and
Prevention (CDC) identified 2 cases of human
infection with a swine-origin influenza A (H1N1)
virus (S-OIV) characterized by a unique
combination of gene segments that had not been
identified among human or swine influenza A
viruses. As of 5 May 2009, cases of human
infection with the same novel virus have also
been identified in Mexico, Canada, and elsewhere.
We report the 1st 643 confirmed cases of human
infection with this virus in the United States.

Methods: Enhanced surveillance was implemented in
the United States for human infection with
influenza A viruses that could not be subtyped.
Specimens were sent to the Centers for Disease
Control and Prevention for real-time
reverse-transcriptase­polymerase-chain-reaction confirmatory testing for S-OIV.

Results: From 15 Apr 2009 through 5 May 2009, a
total of 642 confirmed cases of S-OIV infection
were identified in 41 states. The ages of
patients ranged from 3 months to 81 years; 60
percent of patients were 18 years of age or
younger. Of patients with available data, 18
percent had recently traveled to Mexico, and 16
percent were identified from school outbreaks of
S-OIV infection. The most common presenting
symptoms were fever (94 percent of patients),
cough (92 percent), and sore throat (66 percent);
25 percent of patients had diarrhea, and 25
percent had vomiting. Of the 399 patients for
whom hospitalization status was known, 36 (9
percent) required hospitalization. Of 22
hospitalized patients with available data, 12 had
characteristics that conferred an increased risk
of severe seasonal influenza, 11 had pneumonia, 8
required admission to an intensive care unit, 4
had respiratory failure, and 2 died. The S-OIV
was determined to have a unique genome
composition that had not been identified previously.

Conclusions: A novel swine-origin influenza A
virus was identified as the cause of outbreaks of
febrile respiratory infection ranging from
self-limited to severe illness. It is likely that
the number of confirmed cases underestimates the
number of cases that have occurred.

--
Communicated by:
ProMED-mail


[These 2 papers provide well-documented accounts
of the nature of the viruses circulating prior to
and subsequent to the appearance of the novel
2009 strain of influenza A (H1N1) virus.
Interested readers should consult these papers in conjunction. - Mod.CP]

[see also:
Influenza A (H1N1) - worldwide (18): case counts 20090509.1728
Influenza A (H1N1) - worldwide (17) 20090508.1722
Influenza A (H1N1) - worldwide (16): case counts 20090507.1715
Influenza A (H1N1) - worldwide (15) 20090507.1709
Influenza A (H1N1) - worldwide (14): case counts 20090507.1702
Influenza A (H1N1) - worldwide (13) 20090506.1695
Influenza A (H1N1) - worldwide (12): case counts 20090505.1681
Influenza A (H1N1) - worldwide (11): coincident H3N2 variation 20090505.1679
Influenza A (H1N1) - worldwide (10): case counts 20090504.1675
Influenza A (H1N1) - worldwide (09) 20090504.1673
Influenza A (H1N1) - worldwide (08): case counts 20090503.1660
Influenza A (H1N1) - worldwide (07) 20090503.1658
Influenza A (H1N1) - worldwide (06): case counts 20090502.1654
Influenza A (H1N1) - worldwide (05) 20090503.1657
Influenza A (H1N1) - worldwide (04): case counts 20090501.1648
Influenza A (H1N1) - worldwide (03) 20090501.1646
Influenza A (H1N1) - worldwide (02): case counts 20090430.1638
Influenza A (H1N1) - worldwide 20090430.1636]
....................cp/ejp/dk

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